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SCIENCE 



[N. S. Vol. XXXVII. No. 961 



in 1891. For forty-six years he was an 

 active contributor to Science. The list of 

 his publications, prepared by his nephew, 

 gives 597 titles. A large part of these are 

 brief communications to the Academy of 

 Natural Sciences in Philadelphia, but the 

 list includes also a series of articles and 

 memoirs, some of them of considerable 

 extent, and all valuable. Leidy's investi- 

 gations are among the classics of American 

 science. 



He represents a type of scientific man 

 which seems in our days of specialization 

 and of elaborate laboratories almost ex- 

 tinct. He was a naturalist, and was one 

 of the group of four distinguished true 

 naturalists who have done most for the 

 introduction of natural science into Amer- 

 ican life. These four men — Louis Agassiz, 

 Spencer F. Baird, James D. Dana and 

 Joseph Leidy — were contemporaries. They 

 all took a similar view of nature. She was 

 a whole made up of many parts played 

 together, and they were interested in the 

 whole drama. Their delight was to go 

 forth and see the world and watch the co- 

 ordinated working of its parts. The cor- 

 relation between living beings and physical 

 forces appealed to them. They were quite 

 untouched by what we may call the "labo- 

 ratory spirit, ' ' which has arisen since their 

 time — that spirit which isolates an object 

 or phenomenon indoors in order to apply 

 to it all the finest resources of modern 

 scientific equipment. These men, on the 

 contrary, went out of doors to see and 

 study, and the spoils which they brought 

 home were investigated without any elab- 

 orate appliances. Young zoologists, botan- 

 ists and geologists of to-day find these 

 methods too toilsome. In one passage 

 Leidy points out that the studies of the 

 living fauna of our streams and ponds 

 may be carried on by a simple microscope, 

 such as even our elementary students of 



to-day would scarce deign to use, yet how 

 varied, interesting, and even wonderful the 

 observations which Leidy has recorded! 

 One has only to look through his collected 

 researches in helminthology and parasitol- 

 ogy, published by the Smithsonian Institu- 

 tion in 1904, to gain a clear impression of 

 the enormous extent and variety of these 

 observations. He searched all sorts of 

 animals, insects, vertebrates, molluscs and 

 found a great number of parasitic plants 

 and animals, concerning which he reports 

 many original observations. Many of the 

 species discovered were new to science and 

 were named by him. Nearly the whole of 

 the material he studied was collected by 

 himself, for the most part on little trips he 

 made in the neighborhood of Philadelphia. 

 I quote his own quaint reference to these 

 excursions : 



"Going fishing?" How often the question has 

 been asked by acquaintances, as they have met me, 

 with rod and basket, on an excursion after ma- 

 terials for microscopic study. "Yes!" has been 

 the invariable answer, for it saved much detention 

 and explanation; and now, behold! I offer them 

 the results of that fishing. No fish for the stom- 

 ach, but, as the old French microseopist Joblet 

 observed, ' ' some of the most remarkable fishes 

 that have ever been seen"; and food-fishes for 

 the intellect. 



Although professor of anatomy at this 

 university for a long time (1858-1891), his 

 heart was alwaj^s in his natural-history 

 studies. He did, to be sure, write a text- 

 book of anatomy, undertaken, it is said, 

 only after much urging by the publisher, 

 but it was only an unessential episode in 

 his life. Yet he knew how to use his 

 anatomical opportunities, and he has given 

 us valuable notes on the inter-maxillary 

 bone in man, on the structure of the liver, 

 on reversal of the viscera, etc. But his 

 real life was the exploration of nature. 

 He acquired intimacy not only with ani- 

 mals, the chief objects of his study, but 



